Manufacturing plants, grocery stores, delivery companies all have COVID-19 outbreaks in GTA|CANADA

© Michael Wilson/CBCShoppers wait outside a Toronto shopping centre in early May. Grocery stores, according to local public health units, are among the workplaces facing COVID-19 outbreaks.

Manufacturing plants, grocery stores, delivery companies and other workplaces are all among the settings where community COVID-19 outbreaks are happening across the Greater Toronto Area, according to public health details shared with CBC News.

Now, as more businesses reopen, officials in the epicentre of Ontario's novel coronavirus cases are keeping a close eye on these indoor workplaces — and multiple infectious disease experts agree it needs to be a key focus.

"Work environments where there's lots of people clustered in close proximity, those are just high-risk places for this to be spread," said Dr. Isaac Bogoch, an infectious disease specialist with the University Health Network.

"It would be very smart to have high-risk settings identified now and if there is excess testing capacity, these are the settings where surveillance systems would be of the highest yield."

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Throughout this months-long pandemic, institutional outbreaks — in settings like long-term care homes, retirement homes and hospitals — have largely driven up case counts and dominated headlines.

But some public health units say those cases are now falling, while community outbreaks were observed even before provincial restrictions started lifting.

Various types of indoor workplaces and factory settings are all hot spots, according to the latest details provided to CBC News by Toronto, Durham, York, and Peel region public health units. Halton was also contacted, but officials did not respond to questions by the deadline for this story.

As previously reported, those five GTA regions make up 76 per cent of the roughly 6,600 new confirmed infections across the province in May.

"We still have a very real threat of community-level spread of the virus," said physician epidemiologist Dr. Nitin Mohan, a partner at ETIO Public Health Consultants and adjunct professor at Western University.

2 'clusters of cases' at Toronto grocery stores

Dr. Vinita Dubey, Toronto's associate medical officer of health, said so far, community outbreak investigations in Toronto have focused on essential workplaces and an emergency child care centre.

"Before the restrictions were put in place, social gatherings were often associated with clusters of cases and outbreaks," she added in a statement.

Toronto Public Health is also currently investigating two clusters of cases among staff at grocery stores: a Loblaws at Dupont and Christie, and a Metro in Parkway Mall in Scarborough.

Many of these workers, deemed essential by the province, haven't been able to avoid busy indoor settings and often face socioeconomic challenges, noted Mohan. Neighbourhood-based data recently released by the city suggests a similar trend, with lower-income areas facing high case counts.

"It is disproportionately affecting vulnerable communities," Mohan said.

In Peel region, the local public health unit is tracking "several large workplace clusters" tied to manufacturing plants, warehouses, and delivery companies, along with outbreaks in meat processing plants and correctional facilities, officials said in an email.

Peel officials said they are also now seeing fewer cases in institutions, with a shift toward community-based outbreaks.

"Workplace related outbreaks continue to make up a small proportion of our total confirmed cases; however, we are closely watching this area as the economy moves to further opening," echoed York Region spokesperson Patrick Casey in a statement.

The York public health unit is investigating 45 workplaces with more than two cases tied to possible work-related transmission, though not all of those may wind up being considered outbreaks once the investigations are complete, Casey added.

Officials for Durham also said workplaces and factories are among the community settings experiencing cases.

Province-wide, data shows Ontario is close to hitting 30,000 total confirmed cases since the start of the pandemic, and roughly 61 per cent of cases have been tied to outbreaks or close contacts of confirmed cases — primarily institutional ones, plus those happening in community settings.